1. Technical Field
The present invention generally relates to pneumatic tires and, more particularly, to methods of attaching electronic monitoring devices to the innerliner of a pneumatic tire. Specifically, the present invention relates to a method of preparing the innerliner of a pneumatic tire so that a monitoring device may be securely attached to the innerliner of the tire.
2. Background Information
It is desired in the art to monitor the conditions of tires while they are installed and in use on a particular vehicle. It is particularly desirable to measure tire wear, internal temperature, and internal pressure. Other desirable measurements may be the number of tire rotations that have occurred in given time. These measurements are preferably capable of being taken while the tire is in use without having to remove the tire from the vehicle or otherwise interrupt the use of the vehicle to take the measurements. It is particularly desirable to monitor the conditions and statistics on large off-the-road truck tires because the off-the-road tires are expensive and subject to harsher conditions than typical passenger car tires. The off-the-road tires on large trucks and other vehicles also must be regularly maintained to maximize vehicle efficiency.
Numerous types of such monitoring devices are known in the art. One type of known monitoring device uses a passive integrated circuit embedded within the body of the tire that is activated by a radio frequency transmission that energizes the circuit by inductive magnetic coupling. Other prior art devices used for monitoring tire conditions include self-powered circuits that are positioned external of the tire, such as at the valve stem. Other active, self-powered programmable electronic devices are disclosed in U.S. Pat. Nos. 5,500,065, 5,573,610, 5,562,787, and 5,573,611 which are assigned to the assignee of the present application.
One problem common to each of these monitoring devices is the problem of attaching the monitoring device to the tire. The attachment problem is difficult when the monitoring device is attached to the inside surface of the tire, the outside surface of the tire, or imbedded within the body of the tire. The attachment problem is difficult because the forces on the electronic device are significant and numerous. Tires not only are subjected to rotational forces when the vehicle is moving but also are subjected to various impact forces when the tire contacts bumps or surface irregularities. The attachment of the monitoring device to the tire must be strong enough and secure enough to maintain the position of the monitoring device with respect to the tire while experiencing all of these forces while also protecting the monitoring device from damage resulting from these forces.
Another problem with the attachment of a monitoring device to a tire is that the tire must be balanced about its rotational axis to efficiently perform. The monitoring device itself already adds weight to the tire requiring the tire to be counterbalanced. It is thus desired to minimize the weight of the attachment so that additional counterbalancing weights do not have to be added to the tire. It is thus desired to provide an attachment that is strong and secure while being small and lightweight.
Another problem experienced with attaching a monitoring device to a pneumatic tire is that the surface where the monitoring device is being anchored is often not stable. Tires are designed to flex and stretch to accommodate various pressures and forces. The attachment of the monitoring device to the tire must accommodate the movement and stretching of the tire surface where the monitoring device is connected. Such accommodation must last throughout the life of the tire and function at a wide range of temperatures and pressures.
A further problem experienced in connecting a monitoring device to a pneumatic tire is that tires are manufactured on automated assembly lines. The attachment method must be able to be relatively easily engineered into the existing automated tire assembly lines to be useful. As such, the method of attaching the monitoring device to the pneumatic tire cannot include any manual steps or steps that require precise component manipulation.
Another problem with attaching a monitoring device to a tire is that the innerliner of a pneumatic tire does not readily bond with an adhesive. The material used to fabricate innerliners is selected to create a good fluid-impervious barrier that retains air within the pneumatic tire. The material is not, however, selected because it is conducive to adhesion. There have thus been problems in the art in connecting the relatively heavy monitoring device to the innerliner in a manner that securely anchors the monitoring device without destroying the innerliner. Although buffing the innerliner to create a textured surface is effective with selected innerliners, the innerliners on many tires cannot be buffed because they are too thin. It is thus desired in the art to provide a method for preparing the innerliner of a pneumatic tire so that a monitoring device may be quickly and easily securely attached to the prepared area.